1. Field of the Invention
This invention relates to a new mechanism for selecting the movement of the movable members of a tucked selvedge forming device, particularly suitable for terry looms, which by eliminating any movement by magnetic action and consequently any danger of sticking due to external causes such as dust etc., enables high operating speeds to be attained as required by modern looms, and results in considerable energy and hence cost saving. More specifically, the invention relates to an improvement in the previous U.S. Pat. No. 4,600,039 of Jul. 15, 1986 of the same applicant.
2. Description of the Related Art
According to this patent, a tucked selvedge forming device comprises a movable member for grasping and cutting the weft ends and driven with translational movement in order to grasp said weft ends and cut them to size, and with rotational movement to wrap said weft ends about a second hook-shaped movable member for feedback which is also driven with translational and rotational movement to penetrate into the warp and drag in said weft ends, all said movements being obtained independently of each other by separate levers which, pivoted at one end on one and the same shaft and spring-biassed, are driven by corresponding drive cams also fixed onto one and the same shaft.
As a terry cloth is substantially obtained, in known manner, by firstly inserting several weft yarns, which are carried by the reed into a retracted blind beatup position located generally a few millimeters from the fell of the fabric under formation, and then beating up said already inserted weft yarns, together with a further inserted weft yarn, against said fell, and as the tucked selvedge must be formed only after this last beatup, it is apparent that the ends of the inserted weft yarns are fed back into the shed to form the selvedge only after they have been beaten up by the reed against the fell of the fabric, so excluding feedback during blind beatup. In other words, the movable members provided for the feedback of the inserted weft yarn ends into the shed have to be kept inactive or locked in their rest position until said inserted weft yarns have been beaten up by the reed against the fell of the fabric under formation.
This locking is achieved, according to the teachings of said U.S. Pat. No. 4,600,039 in that said operating levers are provided at their pivoted end with appendices or stop teeth which cooperate with a mechanism for selecting the movement of said movable member, comprising corresponding locking abutments mounted on a support arbor which is electromagnetically movable axially parallel to the pivoting shaft for said operating levers from a position, maintained by a reacting spring, in which said locking abutments engage said teeth, to a position in which they do not engage. In this manner, to achieve feedback of the weft yarns into the shed to form the selvedge and hence the full operation of all the movable members, it is necessary only to energize the electromagnet, which overcomes the action of said reaction spring to move the locking abutments on the arbor out of interference with the teeth of the operating leers.
However, said known selection mechanism suffers from a series of drawbacks, the most serious of which is the considerable mass which has to be moved by the electromagnet, which in addition to consuming a considerable amount of energy does not allow high operating speeds to be attained because of the considerable inertia in play; in addition, because of its configuration the known mechanism is subject to possible sticking due to the ever-present dust which can hinder, if not block, the movement of said arbor.